Abstract: An illuminating reflector is composed of a stick which is adapted to be detachably inserted into a stick holding aperture formed in an illuminator, an actuating runner which pivotally connects a plurality of dome ribs and is slidably inserted onto the stick, a reflection sheet which is put on the ribs and cause diffusingly reflection of light, a fixed collar secured at the top portion of the stick, and struts which are pivoted at their opposite ends respectively to the fixed collar and to the midway of the ribs. Therefore, the reflector can be opened by displacing the runner toward the fixed collar to flare the reflection sheet in a shape of a box, while when removing the runner counterwardly, the reflector can be folded into a compact form.